Privacy policy

Who we are

Tidestill is run by STACK SOFTWARE LIMITED, NZBN 9429053998620, 9a Fenhall Street, Russley, Christchurch 8042, New Zealand. You can reach us at support@tidestill.com. When this policy says “we”, it means STACK SOFTWARE LIMITED.

Tidestill is offered to people in New Zealand and Australia. We follow the New Zealand Privacy Act 2020 and, for people in Australia, the Australian Privacy Principles in the Privacy Act 1988. Our privacy officer looks after this policy and any privacy questions or complaints; you can reach them at support@tidestill.com.

What we get from Google

When you sign in with Google, Google tells us your name, email address, profile photo and Google account ID. We use them to recognise you and to show your name and photo in the app.

When you connect Google Health, you choose which of three read-only permissions to give. For each one you allow, we read:

• Sleep: when you fell asleep and woke, your sleep stages, and the times you were awake in the night.
• Activity and fitness: steps, distance, floors, active minutes, calories, heart-rate zones, workouts and cardio fitness.
• Health metrics and measurements: heart rate (minute by minute), resting heart rate, heart rate variability, breathing rate, blood oxygen, skin temperature, and your weight if you log it.

We can't change anything in your Google account, and we can't see anything else in it: not your location, messages, contacts, photos or files.

Health information is sensitive information. We only collect it with your express consent, which you give when you connect Google Health and choose which permissions to allow. You can withdraw that consent at any time by disconnecting (see Your choices).

What you tell us

• Your settings: time zone, wake time, the sleep you feel you need, units and date format.
• Evening check-ins: the items you track (for example alcohol or caffeine), your answers and any note you add.
• Feedback you send us, the page and device details if you tick the box to include them, and whether you let us look at your data to fix the problem.
• Your email address and watch model if you join the beta waitlist.

Cookies and technical data

We use a few cookies needed for the app to work. On our public pages only, we also use Meta’s pixel to measure our ads, as explained below.

• hs keeps you signed in, for up to 30 days at a time.
• oauth_state and oauth_next protect the sign-in and connect steps and remember where to return; they last 10 minutes.
• oauth_pkce holds a one-time secret that proves the answer coming back from Google belongs to the sign-in or connect step you started; it lasts 10 minutes.
• tz holds your browser's time zone so a new account starts in the right one; it lasts a year.
• trends_range remembers the date range you last chose in Trends; it lasts a year.

Meta pixel. Our home, contact and policy pages load Meta's pixel when you aren't signed in. It sets a cookie called _fbp (it lasts 90 days) and tells Meta that the page was viewed and, if you join the waitlist, that someone signed up. We don't send your email address or anything else you type, and the pixel never runs inside the app, so Meta never receives your health data or anything from your account. Meta uses it to measure and improve our ads under its own privacy policy. You can limit this in your browser or in your Facebook ad settings.

Our servers keep short technical logs (times, pages requested and errors) to keep the service running; our host keeps them for 30 days. We record simple product events in our own database, such as that you signed up, opened the app that day, finished your first sync, or turned a feature on or off. They never contain health data, and we use them only to understand how Tidestill is used and to keep it working. If error reporting is switched on, crash reports go to Sentry with request bodies, query strings, cookies and user details removed. If we measure visits to the public pages, it's with a cookieless counter that stores no personal data.

How we use it

We use your data only to work out and show your scores, plans and insights, to keep your data in sync, and to answer you when you contact us. Specifically:

• We never sell your data, show you ads, use your data for advertising, give it to data brokers, or use it for credit or lending decisions.
• We don't transfer your data to anyone else, except the service providers below who run the app for us, or as described under “When we might share it”.
• No person at STACK SOFTWARE LIMITED reads your health data, except: when you ask us to, by ticking “Let us look at my data to fix this” when you send feedback (for up to 30 days); when it's needed to keep the service secure, for example to investigate abuse; when the law requires it; or after it has been aggregated and anonymised to run the service.
• We don't use your data to train general-purpose AI models. Insights in the app come from fixed rules, not from a language model.
• Your scores and insights are worked out automatically by those rules. They're for your own information and don't decide anything about you, such as access to a service, a price or a credit decision.
• We email you about your account and the service. We only send marketing emails, such as launch news to people on the waitlist, if you've agreed to them, and every one has an unsubscribe link.

When we might share it. We'd give information to police or other authorities only when the law requires it, such as a court order, or when it's needed to prevent a serious threat to someone's life or health; we'll tell you unless the law stops us. If STACK SOFTWARE LIMITED or Tidestill is sold or merged, your data could move to the new owner, who would have to keep following this policy; we'll tell you before that happens, and you can delete your account first.

If you turn on Stress, we fetch your steps minute by minute and use them with your minute-by-minute heart rate to show when your heart rate was raised while you were still. It's worked out by fixed rules, not shown to anyone else, and it isn't medical advice. Turning Stress off deletes your minute steps and Stress readings.

Tidestill's use and transfer to any other app of information received from Google APIs will adhere to the Google API Services User Data Policy, including the Limited Use requirements. See the Google API Services User Data Policy.

The use of information received from Google Health API and/or Developer Tools will adhere to the Google Health API Developer and User Data Policy, including the Limited Use requirements. See the Google Health API Developer and User Data Policy.

Where it's kept

Your data is stored in a Postgres database hosted by Railway in Singapore. It travels over encrypted connections (TLS). The tokens Google gives us to read your data are encrypted in the database with AES-256-GCM.

Some of the service providers below are based in, or store data in, other countries, mainly the United States. We only use providers that protect personal information in ways comparable to New Zealand and Australian privacy law.

We take reasonable steps to protect your information: encrypted connections, encrypted tokens, access to the production systems limited to the people who run Tidestill and protected with two-step sign-in, and regular updates to our software. If a privacy breach is likely to cause you serious harm, we'll tell you and the regulator, as the New Zealand Privacy Act and Australia's Notifiable Data Breaches scheme require.

How long we keep it

• Minute-by-minute heart rate: kept for 365 days, then deleted. Your daily figures stay.
• Daily scores, sleep, workouts, check-ins and their notes: kept while your account is open. Notes can hold anything you write, so they're deleted with your account like everything else.
• Feedback you send: kept while your account is open, so we can follow up. Permission to look at your data lasts 30 days from when you give it.
• Waitlist entries: kept until you create an account, ask us to remove you, or we close the waitlist.
• Server logs: 30 days. Error reports, if error reporting is on: up to 90 days.
• Backups roll off on our host's schedule (to be confirmed before launch).
• When you delete your account, everything above is deleted straight away, and we revoke our access to your Google account. Product analytics events are kept with no link to your name, email or Google account. One record that an account was deleted keeps its random account number, so that if we ever restore a backup we can delete the account again.

Your choices

• Download everything as a spreadsheet or a full JSON file from Settings › Your data.
• Disconnect Google Health in Settings. Syncing stops, and you choose whether to keep the data already here or delete it.
• Delete your account in Settings › Account. See Data deletion for what that removes.
• Remove our access at Google at any time at myaccount.google.com/permissions.
• Ask us what we hold, to correct it or to delete it, by writing to support@tidestill.com. Data that comes from Google Health, like your sleep or heart rate, is corrected at the source: change it in the Google Health app and we'll pick up the change at the next sync.

Complaints. If you're unhappy with how we've handled your information, write to our privacy officer at support@tidestill.com. We'll acknowledge it within 3 working days and give you our answer within 20 working days. If you're still not satisfied, you can complain to the Office of the Privacy Commissioner in New Zealand or the Office of the Australian Information Commissioner in Australia.

Who helps us run it

• Google provides sign-in and the Google Health data you allow.
• Railway hosts the app and the database, in Singapore.
• Google Workspace handles our support email, so emails you send us are stored there.
• Cloudflare runs our domain's DNS and forwards email sent to our support address.
• Meta measures visits to our public pages and waitlist sign-ups from our ads, through its pixel. It never receives health data.
• Sentry receives error reports, with personal details removed, when error reporting is on.
• A cookieless analytics service counts visits to the public pages, if we switch one on.

Age

Tidestill is for people aged 16 or older. If you're younger, please don't use it. If we learn that someone under 16 has an account, we'll delete it.

Changes and contact

If we change this policy in a way that matters, we'll show a notice in the app the next time you open it, and update the date at the top. This version is 2026-10-03.

Questions or requests: support@tidestill.com. We reply within 3 working days, and we complete requests to see or correct your information within 20 working days, as the law requires.